This invention concerns metal finishing barrels used in the cleaning, plating, phosphating, etc. of metal parts in bulk.
A material which will not be attacked by the various processing solutions such as polypropylene or stainless steel is typically used to construct metal finishing barrels, which are perforated so as to allow the parts to be immersed when the barrel is lowered into a tank of a plating or other processing solution. The finishing barrel is rotatably mounted on a support structure to allow it to be rotated while immersed in the tank to tumble the parts insuring even processing, and a gear is affixed to one end of the barrel for driving the barrel with an electric motor.
One or more removable covers are installed over a loading/unloading opening provided in the side of the barrel. The covers must be closely fit to the opening to insure that small parts will not be captured in clearance cracks or escape through gaps between the cover and the barrel. The covers must also be held securely to withstand the heavy loads imposed by the weight of bulk quantities of metal parts as the finishing barrel is rotated.
These requirements have led to the development of an interlocking tab cover securement in which a series of tabs on each side of the cover are slid beneath barrel tabs projecting towards the barrel opening to secure the cover in position. A separate cover locking system is needed to positively prevent the cover from shifting back to release the tabs during processing. This locking system has previously taken the form of a polypropylene nut piece threaded into a gap between two covers arranged in end to end alignment over the opening, preventing the covers from shifting back to disengage the tabs.
This arrangement has worked very well, but requires the threading and unthreading of the separate nut piece, significantly slowing the process of installing and removing the covers manually. Further, this system makes it difficult to automate the cover installation and removal process, which automation is often desirable.
Accordingly, it is an object of the present invention to provide a processing barrel cover locking system which is positive and secure but does not require separately installed locking system components to speed up the installation and removal of the covers.
It is a further object to provide such a cover locking system which is readily compatible with an automated cover handling system.
The above recited objects of the invention, as well as other objects which will be understood upon a reading of the following specification and claims, are achieved by mounting a cover handle assembly including a spring blade attached at one end to the cover. The cover and barrel are each formed with a series of interfit tabs, which allow the cover to be placed into the barrel opening with the tabs offset. When the cover is slid in one direction, the cover tabs are positioned lying partially beneath the barrel tabs to be interengaged and hold the cover over the barrel opening.
The handle assembly is aligned between successive cover tabs to engage a barrel tab when the cover is pushed into place over the barrel opening, but the spring blade mounting allows the handle to be moved out to allow the cover to be advanced so that the cover tabs are positioned beneath the barrel tabs. The cover is then slid to a tab engaged position with the cover tabs partially lying beneath the barrel tabs to secure the cover in position over the barrel opening.
When the handle is released, the spring blade causes the handle assembly to move back down against the cover, with the handle assembly then located just to one side of the barrel tab. The handle assembly has a blocking portion which is then located to one side of that barrel tab, acting to block any reverse shifting of the cover back out from under the barrel tabs, to positively lock the cover in the secured position.
The handle assembly moves away from the cover when the handle is pulled as the cover is being removed against the force generated by the spring blade, to elevate the handle blocking portion above the barrel tab.
This outward movement of the handle assembly allows the cover to be slid back out from under the barrel tabs and then lifted off the barrel opening.
Either one or two covers can be employed, with one cover having a locking handle securing the other cover in position by an end to end abutment of the covers.
This cover locking system can be employed with an automated process of installing and removing the cover. In this application, the cover handle assembly comprises a rod cammed out by a cam on a slide, which also advances a series of rods into bores in respective upright pieces attached to the cover. The cover and rod slides are then advanced further in the same direction by another actuator and slide to move the tabs out of engagement and allow the cover to be lifted out by motion of a third slide and actuator.